Surface construction of catalase-immobilized Au/PEDOT nanocomposite on phase-change microcapsules for enhancing electrochemical biosensing detection of hydrogen peroxide

To address the deterioration in electrochemical biosensing detection of hydrogen peroxide (H2O2) caused by enzymatic inactivation in high-temperature environments, we have developed a novel type of catalase-immobilized electroactive phase-change microcapsules based on a phase change material (PCM) core, an SiO2 shell, and a poly(3,4-ethylenedioxythiophene)/Au nanocomposite layer with the surface-immobilized catalase. The microcapsules not only show a well-defined core–shell microstructure with the desired chemical compositions, but also present a high latent heat capacity of over 130 J/g for thermal regulation. An electrochemical biosensor was established using the microcapsule-modified working electrode to obtain a high electrochemical response to H2O2 through combining the highly electroactive layer with covalently bonded catalase. The developed biosensor achieved an enhanced electrochemical biosensing response to H2O2 through regulating the microenvironmental temperature surrounding the working electrode by the latent heat release of its PCM core to prevent enzymatic inactivation at high temperature. Compared to conventional H2O2 biosensors without thermal management by PCMs, the developed biosensor exhibits a higher sensitivity of 42.85 µA·mM−1·cm−2 and a lower detection limit of 3.56 µM at a high working temperature of 50 °C. The developed biosensor has found practical applications for sensitive detection and accurate determination of H2O2 level in real food and biological samples over a wide temperature range.